Various schemes for displaying three dimensional images (static, or moving images) are known. One well-known scheme simultaneously displays two images which are encoded for the left eye and right eye by means of different optical polarizations, or colors (e.g. red and green). A viewer wears a pair of special glasses which have lenses in front of the left and right eyes. The lenses are arranged to pass only the image intended for that eye, i.e. a left eye sees only the image intended for that eye. Another stereoscopic display technique sequentially presents an image intended for the left eye, and an image intended for the right eye. A user wears a special pair of glasses which are shuttered in synchronism with the displayed images, such that the left eye shutter is open during the period when the left eye image is displayed, and the right eye shutter is open during the period when the right eye image is displayed.
Auto stereoscopic display techniques remove the need for a viewer to wear special glasses. One known scheme uses a flat panel display with multisided slanted ventricular lenses mounted in front of display elements. An example of this kind of display is described in WO07/069195 A2.
Historically, 3D displays have been limited to specialized applications (e.g. medical imaging) or feature film presentation where it is possible to provide bespoke, high cost, display apparatus. There is now considerable interest in delivering stereoscopic content to a much wider audience, including the consumer electronics market. However, an issue with delivering stereoscopic images in a consumer electronics environment is that conventional displays, and display interfaces which connect displays or projectors to media players, have been designed specifically for the display of conventional 2D images.
Schemes for conveying stereoscopic image data within the confines of existing display interfaces have tended to sacrifice part of the active portion of an image to carry additional data necessary to render a stereoscopic image. The WOWvx format developed by Koninklijke Philips Electronics N.V. divides the overall display frame into a number of separate regions where different data can be carried. The overall frame is divided into two sub-frames, arranged side-by-side: a first of the sub-frames carries 2D image data and a second of the sub-frames carries depth information. A header is added to the beginning of the upper left-hand corner of the frame. The image data is carried in a normal manner across a display interface. A display extracts depth data from the second sub-frame and creates a 3D image having a resolution of the first sub-frame. This 3D image can then be ‘stretched’ to occupy the full visible area of the display.
Digital displays and media players are increasingly being equipped with digital display interfaces such as the High Definition Multimedia Interface (HDMI). The present invention seeks to provide an alternative way of delivering stereoscopic image data over a digital display interface.